This invention relates to improvements in cigarettes and more particularly concerns a process for producing cigarettes having an increased capacity to retain tobacco material within the cigarette at the forward "smoking" end and a consequent reduction in "loose ends" exhibited by conventional cigarettes.
Conventionally in the production of cigarette smoking products, a loose mixture of generally elongated tobacco shreds of various lengths is mechanically converged upon entrance into a garniture apparatus which compresses the mixture to a rod-like configuration in preparation for wrapping by a retaining cigarette paper of specialized properties. The mass of shreds within the rod is thereby slightly compacted and retains its integrity in part due to entanglement and random orientation of the shreds.
A filter is generally affixed to one end of the wrapped cigarette structure. Due to this construction, the tobacco material is confined between the retaining paper and the filter except at the forward or smoking extremity of the cigarette. Commonly in the course of handling, i.e., when the cigarettes are placed in sealed packages and shipped from the factory to the distributor and ultimately delivered to the consumer, shreds of tobacco dislodge from the forward extremity of the cigarette. Although most of such dislodged tobacco will be retained within the cigarette package, on occasion further tobacco may fall from the forward end of the cigarette during handling by the smoker prior to lighting. The dislodged tobacco creates both a cleanliness problem, and a loss of valuable smoking material. The ends of those cigarettes which have lost tobacco are generally referred to as "loose ends". Upon lighting, such ends burn uncomfortably quickly, and occasionally cause partially burned pieces of tobacco to fall from the cigarette.
The loose end problem is particularly acute in the case of cigarettes fabricated from a tobacco blend containing expanded lamina tobacco. The expanded tobacco, such as that produced by the process of U.S. Pat. No. 4,336,814, is generally utilized in amounts ranging from about 10% to 30% of the blend for the purpose of increasing cigarette firmness at a given weight of filler in the cigarette, and reducing the delivery level of smoke components. Because such cigarettes contain fewer total shreds, and because the expanded tobacco shreds generally have a relatively low length to width ratio, the forces holding the shreds together are lessened. Any approach toward minimizing loose ends which involves addition of aqueous substances would cause irreversible collapse of the expanded tobacco.
Among early efforts to overcome the loose ends problem were proposals to fabricate cigarettes as integral porous structures having no shred-like components capable of falling from the cigarette wrapper. Such methods, however, require a radical departure from present cigarette manufacturing methods, and further represent a significant change from those cigarette products with which present smokers are familiar.
Other approaches directed to overcoming the occurrence of loose ends have involved efforts to interadhere the tobacco shreds so that they will not fall out of the open forward extremity of the cigarette. Such approaches are difficult to achieve in a successful manner because any significant interadherence of shreds prior to entrance into the cigarette making machine impairs the efficiency of cigarette production. Techniques have also been disclosed which involve adding ingredients to the mixture of shredded smoking material at the instant of its entrance into the garniture of a cigarette making machine. Such techniques, however, are difficult to control at the very high speeds of cigarette formation, especially where uniform treatment of the tobacco is desired.
As one example of an approach to resolving the "loose ends" problem, U.S. Pat. No. 3,136,321 concerns a method for utilizing powdered scrap tobacco which ordinarily would not be retainable by a cigarette as an adhesive agent. The method involves the adherence of the powdered scrap material to water-moistened tobacco leaf or shreds. The moistened tobacco, having 17% to 35% water, has a gumminess adequate to facilitate immediate adherence of powdered scrap. The disadvantages of this method are uneven distribution of adhered scrap additive, staining of the cigarette wrapper by the adhesive agents, and the high moisture level of the tobacco which is incompatible with the use of expanded tobacco.
U.S. Pat. No. 4,009,723 discloses an improved method for cutting tobacco products into cigarettes which involves the use of a laser. According to this teaching, the tobacco filler can be pretreated with a bonding material which caramelizes (i.e., melts and rehardens, or changes chemically) to seal ends when a cigarette is cut with a laser, thereby minimizing loose ends. Sugars and sugar containing materials are suggested for use as the bonding material.
Sugar, carbohydrate additives and other adsorbants have been employed in cigarette making for a variety of purposes including fixing additives onto a cigarette or within the tobacco, but have not been employed in an attempt to overcome the problem of "loose ends". In U.S. Pat. No. 1,972,718 tobacco is treated with a finely divided hydrated aluminum silicate or clay which assertedly permits uniform distribution of heat, increases the water content of tobacco and absorbs liberated gases and tars, thereby improving smoke quality. This silicate powder is also employed to add flavorings to the tobacco. Hygroscopic (moisture-absorbing) compounds have frequently been employed to adhere flavorants or other additives to tobacco, or to absorb toxic substances present in the smoke. See, e.g., U.S. Pat. Nos. 2,114,281; 2,063,014; 4,409,995; 3,008,472; 3,472,237; 4,193,412.
U.S. Pat. No. 1,967,556 discloses applying a hygroscopic flavoring material such as glycerine, honey, or maple sugar to the ends of a cigarette containing tobacco originally devoid of such material. The object of the method is to trap tobacco particles and tars which normally are inhaled by passage through the "mouth" end of the cigarette, but avoid irritating fumes caused by the burning of such sugars.
In U.S. Pat. No. 3,386,450 a method for preventing dust loss from reconstituted tobacco compositions made from tobacco dust employs tobacco pectins dissolved in a solution of sugar and water. The solution is sprayed onto the surface of reconstituted tobacco sheet to retain the dust thereon.
There remains therefore a need in the art for a process for minimizing the occurrence of loose ends in cigarettes, including the uniform treatment of shredded tobacco adaptable to current cigarette fabricating processes and equipment. Additionally there is a need for a process adaptable for the same purpose and usable with blends of shredded tobacco containing expanded tobacco.